Abstract We have investigated the background properties of EPIC-pn
onboard XMM-Newton to establish the background subtraction
method. Count rates of the background vary violently by two orders of
magnitude at the maximum, while during the most quiet period, these
are stable within 8% at a 1
level. The overall spectrum is
dominated by particle events above 5 keV, and its spatial variation
is also found. The long-term variation of the background is also
investigated with CAL CLOSED data, where the filter wheel was in
closed position with the internal calibration source illuminating the
sensitive area. The average background count rate decreased by 20%
from March 2000 to January 2001, but it regained in February 2001.
For the modeling of the background spectrum, we investigate relations
between the 2.0-7.0 keV count rate and some characteristic
parameters. The 2.0-7.0 keV background count rate shows a good
correlation with the count rate of events outside the field of view.
This correlation is usable for the modeling of the background.